Earlier Saturday, she said, she saw her sister and Cepeda holding hands and behaving affectionately. Yemely Rodriguez said she did not hear any commotion before the gunshot that killed her sister.

"There's no way they were arguing," Yemely Rodriguez said. "Nobody was arguing. To me, I think maybe it was an accident or something because maybe if somebody wants to kill somebody, they are not going to do it in front of other people."

Yemely Rodriguez said Cepeda was from Poway. She said she did not know her sister's boyfriend that well, that they had only dated for a few months. She also said he had had a child with another woman.

Yemely Rodriguez said her sister was well-liked, vivacious and "excited to be a mom."

"She would always make everybody laugh," Rodriguez said. "She never said no to anybody when it came to going out. She was really, really happy. She once told someone to live life (fully) because you only live one time."

The young woman said her family ---- seven siblings ---- was raised in Escondido.

"There were seven of us," Rodriguez said. "Now, there are six."

Loarie said he feared that Cepeda might flee to Mexico ---- a suspicion the officer said was based on the proximity of the border, not on any special tie Cepeda may have there.

Escondido police described Cepeda as 5 feet 8 inches tall, about 150 pounds, with brown eyes and "neat" black hair. He reportedly worked in the construction industry.

Authorities urged that anyone with information about the case call the Escondido Police Department at 760-839-4722, regardless of time of day or day of week.